<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        <!--元素选择器-->
        div{
            color:  red;
        }
      /*  类选择器*/
        .cl1{
            color: #dd4eff;
        }
        /*id选择器*/
        #d1{
            color: darkblue;
        }

    </style>

</head>
<body>

<div>div1</div>
<div class="cl1">div2</div>
<div id="d1">div3</div>
</body>
</html>